Fuel battery electric device portable computer and fuel battery drive method

ABSTRACT

Electric power is supplied from a fuel cell to a portable personal computer ( 210 ) having a heat-producing section ( 212 ) which generates heat during operation. The fuel cell includes electrolyte, a fuel electrode and an oxidant electrode arranged to sandwich the electrolyte, and a fuel supply section capable of supplying fuel which has absorbed heat of the heat-producing section ( 212 ) to the fuel electrode. The fuel supply section removes the heat from the heat-producing section ( 212 ) by supplying fuel to the fuel electrode when the fuel is heated by heat exchange. Thus, it is possible to improve the battery efficiency of the fuel cell and suppress increase of the temperature of the heat-producing section.

TECHNICAL FIELD

The present invention relates to a fuel cell, an electric device, aportable computer, and a method for driving a fuel cell.

BACKGROUND ART

Electronic devices such as personal computers handle more and moreincreasing quantity of information and consume markedly increasingamount of electric power in the recent computerized society.Particularly, portable electronic devices consume increasing amount ofelectric power with increasing capacities. Such portable electronicdevices generally use lithium ion cells as an electric power source.However, the energy density of the lithium ion cells has approached itstheoretical limit. To use for a longer time continuously, the portableelectronic device must thereby be reduced in drive frequency of CPU andin electric power consumption.

Under these circumstances, fuel cells having a high energy density and ahigh heat exchange effectiveness are expected to markedly prolong thecontinuous operation hour of the portable electronic devices by usingthem as the electric power source instead of lithium ion cells.

The fuel cells include a fuel electrode, an oxidant electrode and anelectrolyte sandwiched between the electrodes, and generate electricpower by supplying a fuel and an oxidant to the fuel electrode and theoxidant electrode, respectively. Hydrogen gas has been generally used asthe fuel. In addition, methanol-reforming and direct fuel cells havebeen increasingly developed using methanol as a raw material. Suchmethanol is available at low cost and is easy to handle. In themethanol-reforming fuel cells, hydrogen is generated by reformingmethanol. In the direct-methanol fuel cells, methanol is directly usedas the fuel.

When hydrogen is used as the fuel, the reaction in the fuel electrode isin accordance with following Equation (1).3H₂→6H++6e−   (1)

When methanol is used as the fuel, the reaction in the fuel electrode isin accordance with following Equation (2).CH₃OH+H₂O→6H++CO₂+6e−   (2)

In any case, the reaction in the oxidant electrode is in accordance withfollowing Equation (3).3/2O₂+6H++6e−→3H₂O   (3)

Among them, the direct fuel cells can yield hydrogen ions from anaqueous methanol solution, do not require, for example, a reformer, canbe reduced in size and weight and have great advantages for applyingportable electronic devices. In addition, the direct-methanol fuel cellsuse a liquid fuel, i.e., an aqueous methanol solution and have a veryhigh energy density.

The direct fuel cells using methanol directly as the fuel show higherbattery efficiency and power density with an increasing temperature ofthe fuel cell main body and fuel, because the activity of the methanoloxidation reaction increases. Accordingly, the fuel or the like ispreferably heated before supplying to the fuel electrode in the directfuel cells. However, portable electronic devices are difficult to have adedicated heater for heating the fuel or the like due to their limitedusable electric power, and measures must be conventionally taken toimprove their performance under conditions at room temperature or lowtemperatures. The reforming fuel cells must heat methanol to reform thesame to thereby generate hydrogen.

The personal computers and other electronic devices consume more andmore electric power with an increasing drive frequency of their CPU,which invites elevated temperature of the CPU. To solve this problem,the CPU is cooed, for example, by arranging a heatsink for dissipatingthe heat of the CPU and subjecting the CPU to forced air-cooling using acooling fan. However, the air-cooling using a cooling fun producesnoise. The cooling fan consumes much electric power and is not suitablefor use in portable electronic devices limited in usable electric power.Cooling mechanisms must be miniaturized with a decreasing size ofportable electronic devices. However, such miniaturized coolingmechanisms are difficult to yield sufficient cooling power. Accordingly,conventional portable electronic devices are not allowed to have ahigher drive frequency of their CPU for reducing the heat production.Thus, a demand has been also made to provide a method for efficientlycooling a heat-producing part such as a CPU.

The present invention has been accomplished under these circumstances,and an object thereof is to improve the battery efficiency and powerdensity of a fuel cell.

Another object of the present invention is to reduce heat production ofan electric device.

Yet another object of the present invention is to reduce the size andweight of a portable electric device.

A further object of the present invention is to increase the drivefrequency of a CPU of a portable personal computer.

DISCLOSURE OF INVENTION

The present invention provides A fuel cell for supplying electric powerto an electric device including a heat-producing section which producesheat during operation, comprising an electrolyte, a fuel electrode andan oxidant electrode sandwiching the electrolyte, and a fuel-supplysection being configured so as to supply a fuel absorbing the heat ofthe heat-producing section to the fuel electrode. The fuel-supplysection is so configured as to transfer the heat of the heat-producingsection to the fuel to be supplied to the fuel electrode and can supplythe fuel absorbing the heat of the heat-producing section to the fuelelectrode.

The fuel-supply section herein has the function of transferring the heatof the heat-producing section to the fuel and is so configured as totransfer the heat of the heat-producing section to the fuel by anymeans. More specifically, the fuel-supply section may be so configuredas to transfer the heat of the heat-producing section to the fueldirectly or via a heat-conductive material. The fuel-supply sectionincludes, for example, a fuel tank and/or a fuel channel. In this case,the heat of the heat-producing section may be transferred to the fueltank or to the fuel channel.

The heat producing function of the heat-producing section can beimplemented by a part which produces heat when the electric deviceexhibits its original function. The heat of the heat-producing sectioncan be heat of a part which overheats during operation of the electricdevice, or residual heat or waste heat of a part which has been heatedaccording to another object. Thus, the fuel of the fuel cell can beheated without providing, for example, a dedicated heater for heatingthe fuel. The battery efficiency and power density of the fuel cell canbe improved without consuming extra electric power.

The present invention further provides a fuel cell for supplyingelectric power to an electric device including a heat-producing sectionwhich produces heat during operation, comprising an electrolyte, a fuelelectrode and an oxidant electrode sandwiching the electrolyte and afuel-supply section being so configured as to remove the heat of theheat-producing section by the action of a fuel to be supplied to thefuel electrode.

The heat-producing section may be a part which overheats duringoperation of the electric device. The heat-producing section can therebybe cooled by the action of the fuel of the fuel cell. Thus, the electricdevice does not require an extra cooling mechanism, consumes lesselectric power and can be reduced in weight and size.

The fuel may be one that is liquid at ordinary temperature and may beeither of a fuel for a direct fuel cell which is directly supplied tothe fuel electrode or a raw material fuel for a reforming fuel cellbefore reforming. In the reforming fuel cell, the raw material fuel isreformed before use.

The fuel cell may be a direct fuel cell in which the fuel is directlysupplied to the fuel electrode. The battery efficiency and power densityof the direct fuel cell can be increased by heating the fuel. The fuelcell may also be of a polyelectrolyte type in which a polymer membraneis used as a solid electrolyte membrane.

The fuel-supply section may include a flow-rate-control section forcontrolling the flow rate of the fuel to be supplied to the fuelelectrode according to the heat production level of the heat-producingsection. The fuel-supply section may further include a temperaturesensor for detecting the heat production level of the heat-producingsection. The heat production level herein may be indicated by thetemperature of the heat-producing section itself or the temperature ofthe fuel absorbing the heat of the heat-producing section. Theflow-rate-control section may comprise a delivery pump such as apiezoelectric element.

The present invention further provides an electric device having a fuelcell as an electric power source and comprising the fuel cell and aheat-producing section which produces heat during operation of theelectric device, the fuel cell comprising an electrolyte, and a fuelelectrode and an oxidant electrode sandwiching the electrolyte, whereinthe fuel cell further comprises a fuel-supply section being soconfigured as to supply a fuel absorbing the heat of the heat-producingsection to the fuel electrode.

The present invention also provides an electric device having a fuelcell as an electric power source and comprising the fuel cell and aheat-producing section which produces heat during operation of theelectric device, the fuel cell comprising an electrolyte, and a fuelelectrode and an oxidant electrode sandwiching the electrolyte, whereinthe fuel cell further comprises a fuel-supply section being soconfigured as to remove the heat of the heat-producing section by theaction of a fuel to be supplied to the fuel electrode.

The electric device may further comprise a heat-dissipating section, andthe fuel-supply section may further comprise a fuel channel arranged inthe heat-dissipating section. The heat-dissipating section is acomponent for aiding heat dissipation of the heat-producing section. Theheat-dissipating section may comprise, for example, a metal having amultiplicity of radiating fins.

The heat-producing section may be a CPU, and the fuel-supply section maybe so configured as to transfer the heat of the CPU to the fuel. By thisconfiguration, the heat of the CPU can be absorbed by the fuel of thefuel cell, thereby the CPU can be efficiently cooled and the fuel cellcan have increased battery efficiency and power density.

The electric device may further comprise a display, and the fuel cellmay be arranged on the back of the display. The display herein mayinclude a backlight. In this case, the fuel cell is heated by the heatof the backlight of the display, and, thus, the fuel cell can have afurther increased battery efficiency. The fuel electrode in the fuelcell is preferably arranged adjacent to the display. Thus, the airserving as an oxidant can be stably supplied to the oxidant electrode.The electric device may be portable. The electric device of the presentinvention having this configuration has an increased output efficiencyof the electric power source and can have a prolonged continuousoperation hour even when the electric device is portable.

The present invention further provides a portable computer having a fuelcell as an electric power source and comprising a first cabinet having akeyboard section on its surface and holding an electronic circuitincluding a CPU, and a second cabinet being pivotably mounted to thefirst cabinet and including a display being arranged so as to face thekeyboard section, wherein the fuel cell comprises an electrolyte, a fuelelectrode and an oxidant electrode being arranged so as to sandwich theelectrolyte, and a fuel-supply section being so configured as to supplya fuel absorbing the heat of the CPU to the fuel electrode.

The present invention also provides a portable computer having a fuelcell as an electric power source and comprising a first cabinet having akeyboard section on its surface and holding an electronic circuitincluding a CPU, and a second cabinet being pivotably mounted to thefirst cabinet and including a display being arranged so as to face thekeyboard section, wherein the fuel cell comprises an electrolyte, a fuelelectrode and an oxidant electrode being arranged so as to sandwich theelectrolyte, and a fuel-supply section being so configured as to removethe heat of the CPU by the action of a fuel to be supplied to the fuelelectrode.

The portable computer may further include a heat-dissipating sectionbeing so configured as to dissipate the heat of the CPU, and thefuel-supply section may include a fuel channel arranged in theheat-dissipating section.

The portable computer may further include a fuel tank for holding thefuel, and the fuel tank may be arranged at such a position as to absorbthe heat of the CPU.

The present invention further provides a method for driving a fuel cell,comprising the step of cooling a heat-producing section of an electricdevice with a fuel, the electric device having a fuel cell as anelectric power source, and the fuel being supplied to the fuel cell.

The present invention also provides a method for driving a fuel cell,comprising the step of cooing an overheating heat-producing section ofan electric device with a fuel, the electric device having a fuel cellas an electric power source, and the fuel being supplied to the fuelcell.

The present invention further provides a method for driving a fuel cellfor supplying electric power to an electric device, comprising the stepof supplying a fuel to the fuel cell, the fuel absorbing heat of aheat-producing section which produces heat during operation of theelectric device.

The present invention also provides a method for driving a fuel cell forsupplying electric power to an electric device, comprising the steps ofallowing a fuel to be supplied to the fuel cell to absorb heat of aheat-producing section which produces heat during operation of theelectric device to thereby remove the heat of the heat-producingsection, and subsequently supplying the fuel to the fuel cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing a single cell structure ofa fuel cell main body in an embodiment of the present invention.

FIG. 2 is a block diagram showing an example of an electric deviceaccording to an embodiment of the present invention.

FIGS. 3A and 3B are perspective views of a portable personal computeraccording to the embodiment when viewed from different angles.

FIG. 4 is a perspective view showing the detailed structure of a CPUsection in the embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a schematic sectional view showing a single cell structure ofa fuel cell main body in an embodiment of the present invention. Thefuel cell main body 100 includes a plurality of single cell structures101. Each of the single cell structures 101 comprises a fuel electrode102, an oxidant electrode 108 and a solid electrolyte membrane 114. Thesolid electrolyte membrane 114 serves to separate the fuel electrode 102from the oxidant electrode 108 and transfer hydrogen ions therebetween.Thus, the solid electrolyte membrane 114 is preferably a membrane thatcan highly transmit hydrogen ions, is chemically stable and has highmechanical strength.

The material for the solid electrolyte membrane 114 is preferably anorganic polymer having a polar group. Examples of the polar group arestrong acid radicals such as sulfone group and phosphate group, and weakacid radicals such as carboxyl group. Examples of such organic polymersare aromatic fused polymers such as sulfonatedpoly(4-phenoxybenzoyl-1,4-phenylene) and alkylsulfonatedpolybenzimidazole; sulfone-containing perfluorocarbons (Nafion (productof Du Pont; registered trademark), Aciplex (product of Asahi KaseiCorporation)); and carboxyl-containing perfluorocarbons (Flemion SMembrane (product of Asahi Glass Co., Ltd.; registered trademark)).

The fuel electrode 102 and the oxidant electrode 108 comprise afuel-electrode catalyst layer 106 and an oxidant-electrode catalystlayer 112 being arranged on substrates 104 and 110, respectively, andeach containing catalyst-bearing garbon particles and finesolid-electrolyte particles. The surfaces of the substrates 104 and 110may have been subjected to water-repellent treatment.

Examples of the catalyst for the fuel-electrode catalyst layer 106 areplatinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium,cobalt, nickel, rhenium, lithium, lanthanum, strontium, yttrium, andalloys of these metals. The catalyst for the oxidant-electrode catalystlayer 112 can be the same as the fuel-electrode catalyst layer 106, andthe above-exemplified substances can be used. The catalysts for thefuel-electrode catalyst layer 106 and the oxidant-electrode catalystlayer 112 may be the same as or different from each other.

Examples of the carbon particles for bearing the catalyst are acetyleneblack (e.g., Denka Black (product of Denkikagaku Kogyo Inc.; registeredtrademark), XC 72 (product of Vulcan)), Ketjenblack, carbon nanotubesand carbon nanohorns. The particle diameter of the carbon particles isset at, for example, 0.01 to 0.1 μm, and preferably 0.02 to 0.06 μm.

The fine solid-electrolyte particles in the fuel-electrode catalystlayer 106 and the oxidant-electrode catalyst layer 112 may be the sameas or different from each other. The fine solid-electrolyte particlescan comprise a material the same as or different from the solidelectrolyte membrane 114, and such materials can be used in combination.

The substrates 104 and 110 in the fuel electrode 102 and the oxidantelectrode 108 may be a porous substrate such as carbon paper,carbonaceous molded article, carbonaceous sintered article, sinteredmetal or foamed metal. A water-repellent agent such aspolytetrafluoroethylene can be used for the water-repellent treatment ofthe substrates 104 and 110.

The preparation process of the fuel cell main body 100 is notspecifically limited in the present invention and may be, for example,the following process.

Initially, the catalyst is applied to the carbon particles according toa general impregnation procedure. Next, the catalyst-bearing carbonparticles and fine solid-electrolyte particles are dispersed in a mediumto form a paste. The paste is then applied to and dried thereon thesubstrate 104 or 110 which has been subjected to water-repellenttreatment to thereby yield the fuel electrode 102 and the oxidantelectrode 108.

The particle diameters of the carbon particles and the finesolid-electrolyte particles are set, for example, at 0.01 to 0.1 μm and0.05 to 1 μm, respectively. The weight ratio of the carbon particles tothe fine solid-electrolyte particles is set, for example, at 2:1 to40:1. The weight ratio of water to the solute in the paste is set, forexample, at about 1:2 to about 10:1. The particle diameter of thecatalyst particles is set, for example, at 1 nm to 10 nm. The paste canbe applied to the substrate 104 or 110 according to any procedure notspecifically limited, such as blush coating, spray coating or screenprinting. The paste is applied to a thickness of about 1 μm to about 2mm. After applying the paste, the substrate is heated at a settemperature for a set time according to the material used and therebyyields the fuel electrode 102 and the oxidant electrode 108. The heatingtemperature and time are appropriately selected according to thematerial used, and the substrate may be heated at a temperature of 100°C. to 250° C. for 30 seconds to 30 minutes.

The solid electrolyte membrane 114 in the present invention can beprepared by an appropriate process selected according to the materialused. For example, the solid electrolyte membrane 114 of an organicpolymer material can be prepared by dissolving or dispersing the organicpolymer material in a solvent, casting the resulting liquid onto areleasable sheet such as of polytetrafluoroethylene and drying the castfilm.

The above-prepared solid electrolyte membrane 114 is sandwiched andhot-pressed between the fuel electrode 102 and the oxidant electrode 108to thereby yield the single cell structure 101. In this procedure, thefuel-electrode catalyst layer 106 and the oxidant-electrode catalystlayer 112 are brought into contact with the solid electrolyte membrane114. The conditions for hot-pressing are selected according to thematerial. When the fine solid-electrolyte particles in thefuel-electrode catalyst layer 106 and the oxidant-electrode catalystlayer 112 comprise an organic polymer, hot-pressing may be carried outat a temperature exceeding the softening temperature or glass transitiontemperature of the organic polymer. More specifically, hot-pressing iscarried out at a temperature of 100° C. to 250° C., a pressure of 1 to100 kg/cm2 for 10 seconds to 300 seconds.

The single cell structures 101 are arranged in a plane and are connectedin series or parallel to yield the fuel cell main body 100.Alternatively, the single cell structure 101 is sandwiched between afuel-electrode end plate 120 and an oxidant-electrode end plate 122, anda plurality of the resulting article are stacked to yield a stackedstructure in which plural single cell structures 101 are connected inseries. In this case, the fuel cell main body 100 is produced byconnecting the plural stacked structures in parallel.

In the fuel cell main body 100 having the above configuration, a fuel124 is supplied via the fuel-electrode end plate 120 to the fuelelectrode 102 of each single cell structure 101. An oxidant 126 issupplied via the oxidant-electrode end plate 122 to the oxidantelectrode 108 of each single cell structure 101.

The fuel 124 may be an organic liquid fuel including an alcohol such asmethanol, ethanol or dimethyl ether, or a liquid hydrocarbon such ascycloparaffin. The organic liquid fuel can be used as an aqueoussolution. As the oxidant 126, the air is generally used, but oxygen gasmay also be used.

FIG. 2 is a block diagram showing an example of an electric deviceaccording to an embodiment of the present invention.

The electric device according to this embodiment is a portable personalcomputer. The portable personal computer 210 includes a heat-producingsection 212, a heat-dissipating section 226 and a fuel cell serving asan electric power source. The heat-producing section 212 produces heatduring operation of the portable personal computer 210. Theheat-dissipating section 226 is so configured as to dissipate the heatfrom the heat-producing section 212. The fuel cell in this embodimentcomprises the above-mentioned fuel cell main body 100, and a fuel-supplysection. The fuel-supply section supplies a fuel absorbing the heat ofthe heat-producing section 212 to the fuel electrode 102 (FIG. 1) ofeach single cell structure 101 (FIG. 1) of the fuel cell main body 100.The fuel-supply section includes a fuel tank 216, a flow-rate controlsection 218, a temperature sensor 220, a fuel supply piping 222 and afuel recovery piping 224. The fuel tank 216 holds the fuel. Theflow-rate control section 218 controls the flow rate of the fuel to besupplied to the fuel electrode 102 (FIG. 1). The temperature sensor 220detects the heat production level of the heat-producing section 212. Theheat-dissipating section 226 includes a fuel channel.

The above-mentioned fuel cell main body 100, the fuel tank 216 and thepipings 222 and 224 associated therewith constitute a fuel cell system.

Examples of the heat-producing section 212 are CPUs, hard disks, powersupply modules, memories, displays and peripheral devices. Inparticular, overheat of CPU must be avoided. Accordingly, the CPU can beefficiently cooled and the fuel is heated more effectively by coolingthe CPU with the fuel to be supplied to the fuel cell main body 100.

FIGS. 3A and 3B are perspective views of a portable personal computeraccording to this embodiment when viewed from different angles. Theportable personal computer 210 includes a first cabinet 232 which mayhave, for example, a keyboard, and a second cabinet 234 which may have,for example, a display. For the sake of explanation, the portablepersonal computer is illustrated in which operation parts such askeyboard are detached. The second cabinet 234 is pivotably mounted tothe first cabinet 232. The portable personal computer 210 comprises asupport member 239 for supporting the main body.

The portable personal computer 210 includes, for example, a CPU 236 anda hard disk 238. Once the portable personal computer is operated, theCPU 236 and the hard disk 238 produce heat. The fuel-supply sectionremove the heat of the CPU 236 and the hard disk 238 as theheat-producing section 212 by the action of the fuel.

The fuel cell main body 100 in this embodiment is arranged on the backof a display 240. The display 240 is not limited to a liquid crystaldisplay. However, when the display is a liquid crystal display withbacklighting, the heat production of the backlight also raise thetemperature of the fuel cell main body 100, and the output can befurther increased. Thus, the heat of the display 240 is removed, and theportable personal computer can be operated stably. The fuel cell mainbody 100 may also be arranged in the vicinity of the heat-producingsection 212 such as the CPU 236 as another embodiment.

The fuel tank 216 is arranged on the back of the keyboard, namely, onthe back of a face on which the heat-producing section 212 such as theCPU 236 and/or the hard disk 238 is mounted. Thus, the fuel tank 216 isalso heated by the heat of the heat-producing section 212, and theheating of the fuel and removing of the heat of the heat-producingsection 212 can be more efficiently performed.

The flow-rate control section 218 may be, for example, a delivery pump.The flow rate of the fuel to be supplied to the fuel cell main body 100is relatively as small as about 10 cc/min or less. Thus, the deliverypump can be a piezoelectric element such as a miniaturized piezoelectricmotor. Such a piezoelectric element consumes very low electric power.Accordingly, the heat-producing section 212 can be more efficientlycooled with lower energy consumption than the conventional process ofcooling with a cooling fan. In addition, the cooling mechanism does notuse a fan and thereby does not produce noise.

The temperature sensor 220 shown in FIG. 2 is, for example, athermistor. The flow-rate control section 218 controls the flow rate ofthe fuel, for example, according to a PID system depending on thetemperature of the heat-producing section 212 such as the CPU 236. Thus,the fuel at a preferred temperature is supplied to the fuel cell mainbody 100. The preferred temperature of the fuel to be supplied to thefuel cell main body 100 is 30° C. to 100° C.

FIG. 4 is a perspective view showing the detailed structure of the CPUsection in this embodiment. The heat-dissipating section 226 is, forexample, a heatsink. A fuel channel is arranged in meandering manner inthe heat-dissipating section 226. Thus, heat can be more efficientlyexchanged between the CPU 236 and the fuel. The channel in theheat-dissipating section 226 may comprise an aluminum pipe. When theheat-dissipating section 226 is, for example, an aluminum heatsink, thechannel in the heat-dissipating section 226 can be formed integrallywith the heat-dissipating section 226. When the heat-dissipating section226 and the channel therein are made of aluminum, the portion to be incontact with the fuel, such as the inside of the aluminum pipe, can bemade of a material that is resistant to corrosion by the fuel, such asgold plating.

Next, the operation for supplying electric power to the portablepersonal computer 210 by the fuel cell will be described with referenceto FIGS. 1 to 4. The fuel held in the fuel tank 216 is supplied via thefuel supply piping 222 to the heat-dissipating section 226 which isconnected to the heat-producing section 212 such as the CPU 236 and thehard disk 238. The heat of the heat-producing section 212 is absorbed bythe fuel during the course of passing through the fuel channel in theheat-dissipating section 226. Thus, the heat-producing section 212 isefficiently cooled and the fuel is heated. After absorbing the heat fromthe heat-producing section 212, the fuel is supplied via the fuel supplypiping 222 to the fuel electrode 102 of each single cell structure 101in the fuel cell main body 100. The oxidant electrode 108 of each singlecell structure 101 in the fuel cell main body 100 takes oxygen in theair therein to thereby generate electric power. The fuel not used in thefuel cell main body 100 is returned via the fuel recovery piping 224 tothe fuel tank 216.

According to this embodiment, the heat-producing section 212 such as theCPU 236 can be efficiently cooled, and the output of the fuel cell canbe increased by using the waste heat thereof. Thus, problems whichinhibit the application of a CPU with high drive frequency to aconventional portable personal computer can be solved at once, and evena portable personal computer can use a CPU with high drive frequency.

The fuel cell of the present invention will be illustrated in furtherdetail with reference to several examples below, which are not intendedto limit the scope of the present invention.

EXAMPLE 1

A fuel cell main body was prepared in the following manner. Nafion 117(product of Du Pont) was used as the solid electrolyte membrane 114shown in FIG. 1. Denka Black (product of Denkikagaku Kogyo Inc.), aplatinum-ruthenium alloy, and a 5% Nafion solution in alcohol (productof Aldrich Chemical) were used as the carbon particles, the catalyst andthe fine solid-electrolyte particles in the fuel electrode and theoxidant electrode, respectively. Carbon Paper (product of TorayIndustries, Inc.; TGP-H-120) was used as the substrate both in the fuelelectrode and the oxidant electrode.

Initially, Denka Black bearing the catalyst was mixed with the 5% Nafionsolution in alcohol, was dispersed in an ultrasonic disperser at 50° C.for about three hours and thereby yielded a paste. The Nafion 117 samplepaste as the solid electrolyte membrane 114 was applied to Carbon Paperby screen printing, was dried at 100° C. and thereby yielded a fuelelectrode and an oxidant electrode. These fuel electrode and oxidantelectrode were hot-pressed onto the both sides of Nafion 117 and therebyyielded a single cell structure. The areas of the fuel electrode andoxidant electrode were set at 6 cm², respectively. A 20% aqueousmethanol solution as the fuel and the air were supplied to the fuelelectrode and the oxidant electrode of the single cell structure,respectively, thus yielding an output voltage of 0.42 V at an electriccurrent of 600 mA.

A plurality of the above-prepared single cell structure were connectedin a plane in series and parallel and thereby yielded a fuel cell mainbody 25 cm wide, 18 cm long and 0.7 cm thick. A 10% aqueous methanolsolution was charged into a fuel tank 25 cm wide, 5 cm long and 1.5 cmhigh.

The fuel cell main body and fuel tank were aligned on the back of akeyboard of a portable personal computer. The fuel cell main body wasarranged so that the oxidant electrode of the fuel cell was on thedownside of the fuel cell main body, namely, on the side opposite to theportable personal computer. A space (clearance) of about 3 mm wasarranged under the portable personal computer. The portable personalcomputer was so configured that the aqueous methanol solution passesthough the heat-dissipating section of the CPU. The aqueous methanolsolution was supplied to the fuel electrode of the fuel cell main bodyat a flow rate of 1 to 2 cc/min. Temperature sensors were arranged inthe fuel supply piping 222 in the vicinity of the fuel cell main bodyand on the surface of the CPU. The temperature sensors work to measurethe temperature of the aqueous methanol solution immediately beforereaching the fuel cell main body and the surface temperature of the CPU.

When the portable personal computer was not operated, namely, the CPUwas at a standstill, the temperature of the aqueous methanol solutionimmediately before reaching the fuel cell main body was about 20° C.(room temperature). When the aqueous methanol solution was suppliedwhile the portable personal computer and its CPU were operated, thetemperature gradually increased and reached about 50° C. 30 minutesafter the actuation. The surface temperature of the CPU could be held toabout 60° C. This configuration avoids noise even when the aqueousmethanol solution was supplied, since the delivery pump is of small sizeand does not significantly produce noise as compared with the case wherea fan is used. In contrast, the surface temperature of the CPU rose toabout 80° C. when the aqueous methanol solution was not supplied duringoperation of the CPU.

Next, the output of the fuel cell main body 100 was determined and wasfound to be 15 W when the CPU was not operated. The output increasedwhen the CPU was actuated, and became stable at about 23 W 10 minuteslater.

As is described above, the portable personal computer according to thisexample uses a liquid fuel for the fuel cell for cooling itsheat-producing section, especially its CPU, and then supplies the fuelto the fuel electrode of the fuel cell main body. Thus, the temperaturerise in the heat-producing section can be efficiently suppressed, andthe output of the fuel cell as the electric power source can beincreased.

EXAMPLE 2

Single cell structures were prepared by the procedure of Example 1. Aplurality of the above-prepared single cell structures were connected ina plane in series and parallel and thereby yielded a fuel cell main body26 cm wide, 20 cm long and 0.6 cm thick. A 15% aqueous methanol solutionwas charged into a fuel tank 25 cm wide, 6 cm long and 2 cm high.

The fuel tank was arranged in a lower part of a portable personalcomputer, and the fuel cell main body was arranged on the back of aliquid crystal display so that the oxidant electrode of the fuel cellwas on the top of the fuel cell main body, namely, on the opposite sideto the liquid crystal display. In this configuration, the oxidantelectrode can take the air therein. The portable personal computer wasso configured that the aqueous methanol solution passes through theheat-dissipating section of the CPU. The aqueous methanol solution wassupplied to the fuel electrode of the fuel cell main body at a flow rateof 1 to 2 cc/min.

The temperature of the aqueous methanol solution immediately beforereaching the fuel cell main body was about 20° C. (room temperature)when the portable personal computer was not operated, and graduallyincreased and reached about 50° C. after 30 minutes when the aqueousmethanol solution was allowed to pass during operation of the portabledevice. The surface temperature of the CPU could be held to about 60° C.

Next, the output of the fuel cell main body was determined and was foundto be about 18 W when the backlight of the liquid crystal display wasnot used and the CPU was not operated. The output increased and becamestable at about 26 W 10 minutes after the actuation of the CPU, andfurther increased and reached about 30 W 10 minutes after actuation ofthe CPU and the backlight of the liquid crystal display. In thisprocedure, the temperature of the fuel cell main body stood at 50° C. orhigher.

The portable personal computer according to this embodiment uses theliquid fuel for fuel cell for cooling its heat-producing section, inparticular, its CPU, then supplies the fuel to the fuel electrode of thefuel cell main body, and further heats the fuel cell main body by theheat of the backlight of the liquid crystal display. Thus, the fuel cellas the electric power supply can produce a further increased output. Inaddition, the fuel cell main body is arranged on the top of the portablepersonal computer, and the air can be easily taken in the oxidantelectrode.

The present invention has been illustrated above based on the examples.However, these examples are shown only by illustration, and one skilledin the art can understand that various modifications in individualcomponents and treating processes are possible and that suchmodifications are also within the scope of the present invention. Suchexamples will be illustrated below.

In the above embodiments, the electric device is illustrated by taking aportable personal computer as an example but may be a portableelectronic device such as PDA or mobile phone or a desktop electronicdevice such as a desktop personal computer. This is because theseelectronic devices also have a CPU, the fuel of the fuel cell can beused for cooling the CPU, and the performance of the fuel cell can beincreased by heating the fuel with the CPU. Further, the electric devicecan be an electric product such as cleaner or smoothing iron, becausesuch electric products also have a heat-producing section such as apower supply unit, and the performance of the fuel cell can be increasedby heating the fuel with the heat-producing section.

A direct fuel cell has been illustrated as an example in theembodiments. In the direct fuel cell, an organic liquid fuel such asmethanol is directly supplied to the fuel electrode. However, the heatof a component inherently provided in an electric device can also beused as heating means for reforming an organic liquid fuel in areforming fuel cell using, for example, a reformer. In addition, theheat of an overheating component such as a CPU can be removed by usingan organic liquid fuel before reforming.

According to the present invention described above, the heat-producingsection can be efficiently cooled and the output of the fuel cell can beincreased by heat exchange between the heat-producing section of theelectric device and the fuel to be supplied to the fuel cell in the casewhere the fuel cell supplies electric power to the electric device.Thus, a small-sized fuel cell with high power can be provided. Inparticular, the present invention can solve conventional problems inportable computers, namely, electric power deficit and overheat of theCPU concurrently, and the resulting portable computers can employ a CPUwith high drive frequency.

Industrial Applicability

The present invention can be simply applied to an electric device suchas a portable computer, can increase the battery efficiency of a fuelcell, suppress the temperature increase of the electric device andthereby enable the electric device to operate at high speed for a longtime. The present invention can also be applied to other devices inaddition to such portable electric devices.

1-18. (canceled)
 19. An electric device comprising at least a heat-producing section which produces heat during operation; a heat-dissipating section which is arranged adjacent to the heat-producing section for removing heat produced in the heat-producing section; and a fuel cell which serves as an electric power source and uses a fuel being liquid at ordinary temperature, wherein the fuel cell comprises a fuel-supply section and a power-generating section, and wherein at least part of the fuel-supply section is arranged in the heat-dissipating section.
 20. The electric device according to claim 1, wherein the fuel-supply section comprises a fuel tank and a fuel channel, and wherein at least part of the fuel channel is arranged in the heat-dissipating section.
 21. The electric device according to claim 2, wherein the fuel tank is arranged at such a position as to absorb the heat of the heat-producing section.
 22. The electric device according to claim 2 or 3, wherein the heat-dissipating section, the heat-producing section and the fuel tank are stacked.
 23. The electric device according to any one of claims 1 to 3, wherein the fuel-supply section comprises a flow-rate-control section for controlling the flow rate of a fuel to be supplied according to the heat production level of the heat-producing section.
 24. The electric device according to any one of claims 1 to 3, wherein the electric device further comprises a display section, and wherein the heat-producing section comprises an information processing section which houses an electronic circuit including a CPU.
 25. The electric device according to claim 6, wherein the power-generating section is arranged adjacent to the heat-producing section or the display section.
 26. The electric device according to claim 6, wherein the power-generating section comprises at least an electrolyte, a fuel electrode and an oxidant electrode sandwiching the electrolyte, and wherein the fuel electrode is arranged adjacent to the display section.
 27. A method for driving the electric device of claim 1, comprising the steps of cooling the heat-producing section with a liquid fuel supplied to the fuel-supply section being arranged in the heat-dissipating section, and supplying the liquid fuel absorbing heat of the heat-producing section to the power-generating section.
 28. A fuel cell for supplying electric power to an electric device including a heat-producing section which produces heat during operation, comprising a fuel-supply section and a flow-rate-control section, the fuel-supply section being so configured as to supply a fuel absorbing heat of the heat-producing section to the fuel electrode, and the flow-rate-control section controlling the flow rate of the fuel to be supplied to the fuel electrode according to the heat production level of the heat-producing section.
 29. The fuel cell according to claim 10, wherein the fuel is liquid at ordinary temperature.
 30. The electric device according to claim 4, wherein the fuel-supply section comprises a flow-rate-control section for controlling the flow rate of a fuel to be supplied according to the heat production level of the heat-producing section.
 31. The electric device according to claim 4, wherein the fuel-supply section comprises a flow-rate-control section for controlling the flow rate of a fuel to be supplied according to the heat production level of the heat-producing section.
 32. The electric device according to claim 5, wherein the fuel-supply section comprises a flow-rate-control section for controlling the flow rate of a fuel to be supplied according to the heat production level of the heat-producing section. 